A Uridine Glucuronosyltransferase 2B7 Polymorphism Predicts Epirubicin Clearance and Outcomes in Early-Stage Breast Cancer.

BACKGROUND: Epirubicin is metabolized by uridine glucuronosyltransferase 2B7 (UGT2B7), an enzyme rich in single nucleotide polymorphisms (SNPs). We studied whether the -161 C > T germline SNP in UGT2B7 was related to epirubicin metabolism and whether differences exist in the toxicity and efficacy of epirubicin-based chemotherapy among patients who were TT homozygotes, CT heterozygotes, and CC homozygotes. PATIENTS AND METHODS: A total of 132 women with non-metastatic breast cancer receiving FEC (5-fluorouracil 500 mg/m(2), epirubicin 100 mg/m(2), cyclophosphamide 500 mg/m(2)) were prospectively enrolled. Toxicity was assessed in cycle 1 using the National Cancer Institute Common Toxicity Criteria, version 2.0. RESULTS: The sequence at -161 was studied in 132 subjects; 37 were TT homozygotes, 63 were CT heterozygotes, 26 were CC homozygotes, and 6 could not be genotyped. The CC genotype patients had decreased epirubicin clearance (median, 103.3 L/hr) compared with the CT/TT genotype patients (median, 134.0 L/hr; P = .002). The CC homozygous patients had an increased risk of grade 3 to 4 leukopenia compared with the TT homozygotes or heterozygotes (P = .038 and P = .032, respectively). TT homozygotes or heterozygotes had an increased risk of early recurrence (P = .039; χ(2) test). CONCLUSION: The results of the present prospective pharmacogenetic study suggest that the UGT2B7 -161 C > T SNP correlate with drug metabolism, toxicity, and efficacy in patients receiving epirubicin chemotherapy. Further studies of this UGT2B7 SNP as a predictor of epirubicin toxicity and efficacy are warranted.

Association of DNA repair and steroid metabolism gene polymorphisms with clinical late toxicity in patients treated with conformal radiotherapy for prostate cancer.

OBJECTIVE: To explore the possible relationship between single nucleotide polymorphisms (SNP) in candidate genes encoding DNA damage recognition/repair/response and steroid metabolism proteins with respect to clinical radiation toxicity in a retrospective cohort of patients previously treated with three-dimensional conformal radiotherapy (3-DCRT) for prostate cancer. EXPERIMENTAL DESIGN: One hundred twenty-four patients with prostate cancer underwent 3-DCRT at our institution between September 1996 and December 2000. Of these, 83 consented for follow-up of blood sampling and SNP analysis. Twenty-eight patients were documented as having experienced grade >/=2 late bladder or rectal toxicity (scoring system of Radiation Therapy Oncology Group) on at least one follow-up visit. We analyzed 49 SNPs in BRCA1, BRCA2, ESR1, XRCC1, XRCC2, XRCC3, NBN, RAD51, RAD52, LIG4, ATM, BCL2, TGFB1, MSH6, ERCC2, XPF, NR3C1, CYP1A1, CYP2C9, CYP2C19, CYP3A5, CYP2D6, CYP11B2, and CYP17A1 genes using the Pyrosequencing technique. RESULTS: Significant univariate associations with late rectal or bladder toxicity (grade >/=2) were found for XRCC3 (A>G 5' untranslated region NT 4541), LIG4 (T>C Asp(568)Asp), MLH1 (C>T, Val(219)Ile), CYP2D6*4 (G>A splicing defect), mean rectal and bladder dose, dose to 30% of rectum or bladder, and age <60 years. On Cox multivariate analysis, significant associations with toxicity were found for LIG4 (T>C, Asp(568)Asp), ERCC2 (G>A, Asp(711)Asp), CYP2D6*4 (G>A, splicing defect), mean bladder dose >60 Gy, and dose to 30% of rectal volume >75 Gy. CONCLUSIONS: In this study, we identified SNPs in LIG4, ERCC2, and CYP2D6 genes as putative markers to predict individuals at risk for complications arising from radiation therapy in prostate cancer.